In the 20th century, creating American infrastructure meant building the Interstate system, but today, the era of massive road expansion is largely over. Now, engineers and planners are working on how to use the infrastructure we have most efficiently. This doesn’t mean just repairing roads, though that is an essential piece of the puzzle. Rather, new advancements in construction, design, and technology promise to revolutionize how we move people and goods on roads, on rails, and through the air. Cities and states across the country are experimenting with different strategies to maintain and modernize their infrastructure, spurred by the challenges caused by decades of underinvestment.